title: Surveillance of avian influenza virus type A in semi-scavenging ducks in Bangladesh.
abstract: BACKGROUND
  Ducks are the natural reservoir of influenza A virus and the central host for highly pathogenic avian influenza (H5N1), while domestic ducks rearing in semi-scavenging system could serve as re-assortment vessels for re-emerging new subtypes of influenza viruses between birds to human. Avian influenza virus (AIV) surveillance in Bangladesh has been passive, relying on poultry farmers to report suspected outbreaks of highly pathogenic H5N1 influenza. Here, the results of an active surveillance effort focusing on the semi-scavenging ducks are presented.
  
  
  RESULTS
  A total of 2100 cloacal swabs and 2100 sera were collected from semi-scavenging ducks from three wintering-sites of Bangladesh during three successive winter seasons, December through February in the years between 2009 and 2012. Virus isolation and identification were carried out from the cloacal swabs by virus propagation in embryonated hen eggs followed by amplification of viral RNA using Avian influenza virus (AIV) specific RT-PCR. The overall prevalence of avian influenza type A was 22.05% for swab samples and 39.76% ducks were sero-positive for avian influenza type A antibody. Extremely low sero-prevalence (0.09%) of AIV H5N1 was detected.
  
  
  CONCLUSIONS
  Based on our surveillance results, we conclude that semi-scavenging ducks in Bangladesh might play important role in transmitting Avian Influenza virus (AIV) type A. However, the current risk of infection for humans from domestic ducks in Bangladesh is negligible. We believe that this relatively large dataset over three winters in Bangladesh might create a strong foundation for future studies of AIV prevalence, evolution, and ecology in wintering sites around the globe.
authors.affiliation: Faculty of Veterinary and Animal Sciences, Sylhet Agricultural University, Sylhet 3100, Bangladesh. rahmanmm.dpp@sau.ac.bd.
authors.forename: Amina
authors.initials: A
authors.lastname: Khatun
authors.forename: Mohammed
authors.initials: M
authors.lastname: Giasuddin
authors.forename: Kazi Mehetazul
authors.initials: KM
authors.lastname: Islam
authors.forename: Sazeda
authors.initials: S
authors.lastname: Khanom
authors.forename: Mohammed Abdus
authors.initials: MA
authors.lastname: Samad
authors.forename: Mohammad Rafiqul
authors.initials: MR
authors.lastname: Islam
authors.forename: Monira
authors.initials: M
authors.lastname: Noor
authors.forename: Jamal Uddin
authors.initials: JU
authors.lastname: Bhuiyan
authors.forename: Won-Il
authors.initials: WI
authors.lastname: Kim
authors.forename: Seong Kug
authors.initials: SK
authors.lastname: Eo
authors.forename: Md Masudur
authors.initials: MM
authors.lastname: Rahman
mesh_terms: D000818:Animals; D001459:Bangladesh; D004372:Ducks; D053124:Influenza A Virus, H5N1 Subtype; D009980:Influenza A virus / Q000145:classification / Q000302:isolation & purification*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D016036:Seroepidemiologic Studies